Beginning on 12 January several news reports stated that increased volcanic activity occurred at Santa Ana volcano. The Washington VAAC reported that an eruption occurred at 1800 on 16 January that sent ash to ~3.7 km a.s.l. Local observations by volcanologists revealed that an eruption did not occur and no new lava or magma was in the summit crater. Glowing cracks that were visible at night were determined to be an existing fumarole field with measured temperatures of 550 °C. Scientists believe that a magnitude 7.7 earthquake that occurred off the coast of Central America at 1133 on 13 January, killing several hundred people, did not cause an increase in activity at the volcano. Since 12 January there have been reports of increased gas emissions and the volcano is being closely monitored for any changes in activity.

Geological Summary. Santa Ana (also known as Ilamatepec), is a massive, dominantly andesitic-to-trachyandesitic stratovolcano in El Salvador immediately W of Coatepeque Caldera. Collapse during the late Pleistocene produced a voluminous debris avalanche that swept into the Pacific Ocean, forming the Acajutla Peninsula. Reconstruction of the volcano subsequently filled most of the collapse scarp. The broad summit is cut by several crescentic craters, and a series of vents and cones have formed along a 20-km-long fissure system that extends from near the town of Chalchuapa NNW of the volcano to the San Marcelino and Cerro la Olla cinder cones on the SE flank. Small to moderate explosive eruptions from both summit and flank vents have been documented since the 16th century. The San Marcelino cinder cone on the SE flank produced a lava flow in 1722 that traveled 13 km E.

Sources: US Geological Survey Volcano Disaster Assistance Program (VDAP), La Prensa Grafica, Diario del Hoy (elsalvador.com), Washington Volcanic Ash Advisory Center (VAAC), US Geological Survey Earthquake Hazards Program